package edu.fiu.ann.costfunction;

/**
 * The cost function that guide the weight update.
 *
 * @author Yexi Jiang (http://users.cis.fiu.edu/~yjian004/)
 * @date 2011-4-4
 */
public abstract class CostFunction {
	
	/**
	 * Calculate the partial derivative of the cost function.
	 * @param realValue	the real value
	 * @param estValue	the estimated value
	 * @return	the result of partial derivative
	 */
	abstract public double partialDerivative(double realValue, double estValue);
}
